n 2008, the cumulative cost growth in the Department of Defense's portfolio of 96 major defense acquisition programs was $296 billion and the average delay in delivering promised capabilities to the warfighter was 22 months. These poor outcomes mean that other critical defense and national priorities may go unfunded and that warfighters may go without the equipment they need to counter the changing threats that they face. GAO has examined extensively the issues in DOD's weapon system programs from the perspective of best practices in product development, and believes that significant improvements are possible. Because the ability to measure knowledge, processes, and outcomes is critical to achieving these improvements, GAO has used metrics to review the management and health of these programs from within the framework of best practices. This testimony discusses: 1) "knowledge metrics," used to determine how well programs manage technology, design, and manufacturing risks; 2) outcome metrics--concerning cost, schedule, and capability--that serve as "health indicators" of how well programs are being executed in terms of predicted outcomes; and 3) the prerequisites that GAO believes must be met in order for a program's plans and goals to be realistic.